Vibratory type of synchronous converter



p 27, 1966 T. T. HIGHLEY, JR., ET AL 3,275,781

VIBRATORY TYPE OF SYNCHRONOUS CONVERTER Filed July 22, 1964 3 Sheets-Sheet 1 S W. ROSS J. WILLIAMS JR.

AGENT Sept. 27, 1966 T. T. HIGHLEY, JR. ETAL 3,275,78I

VIBRATORY TYPE OF SYNCHRONOUS CONVERTER 5 Sheets-Sheet 2 Filed July 22, 1964 FIG. 3

Sept. 27, 1966 T. T. HIGHLEY, JR.. ETA!- 3,275,781

VIBRATORY TYPE OF SYNCHRONOUS CONVERTER Filed July 22, 1964 5 Sheets-Sheet 5 FIG. 4

United States Patent 3,275,781 VIBRATORY TYPE OF SYNCHRONOUS CONVERTER Thomas T. Highley, Jr., and Morris Joseph, Philadelphia, Charles W. Ross, Hatboro, and Albert J. Williams, Jr., Philadelphia, Pa., assignors to Leeds and Northrup Company, Philadelphia, Pa., a corporation of Pennsylvania Filed July 22, 1964, Ser. No. 384,351 20 Claims. (Cl. 200-166) This invention relates to devices for closing and opening electrical circuits and more specifically to synchronous converters of the vibratory reed type such as generally used for converting direct current to alternating current.

The synchronous converter must necessarily be constructed so that its contacting surfaces continue to make good electrical contact after years of operation even though the surfaces are separated and remade sixty times each second or more. In addition to the stability of their electrical characteristics, it is also desirable that the contact timing should remain stable over long periods of time without adjustment.

The stability of the electrical characteristics has been the subject of considerable research and development Work for a number of years. One of the more diflicult problems which has made such stability hard to achieve concerns the maintenance of clean contact surfaces.

The problem of obtaining stability in timing has been solved in the past by running the synchronous converters for an extended period of time during an initial run-in period before making a final adjustment of the contact timing so that the major portion of the expected change in the actuating elements occured before the converters were put to use. After that initial period the contact timing usually remained essentially stable, however such requirements increased the expense of manufacture and did not always provide for the desired long term stability. Use of the present invention has made it possible to greatly reduce the length of time required for the run in period.

It is an object of this invention to provide an improved contact device which will maintain good electrical contact and stable contact timing over a long period without adjustment.

A further object of this invention is to provide a contact device in which a movable contact is separated from and allowed to remake with a fixed contact in such a manner that an effective wiping action occurs between the contacting surfaces.

It is a further object of this invention to provide a means for separating a movable contact from a fixed contact by the application of force to the movable contact by a pusher so as to cause such separation with a minimum of wear on the pushed element as well as on the movable contact or pushed element to which the force is applied.

A further object of this invention is the arrangement of a stationary and a movable contact so as to minimize the bounce of the movable contact upon a making of the contacts.

To carry out these objects the invention utilizes a stationary contact which has a contacting surface and a movable contact which also has a contacting surface. The movable contact has its contacting surface near one end and its other end is fixed. So as to allow movement of its contacting surface into and out of contact wtih the contacting surface of the stationary contact, the movable contact is constructed so that a portion of its length just adjacent to the fixed end is resilient or flexible in nature and has the characteristics of a flat spring. The movable contact is separated from the stationary contact by the application of a varying force to the movable 3,275,781 Patented Sept. 27, 1966 "ice contact at a .point between its fixed end and its contacting surface and it is so constructed and mounted that upon the application of that force tending to separate the contacting surfaces the movable contact tends initially to move about an instantaneous center which lies in the plane of the resilient or flexible portion. This motion is in a direction to cause motion of thecontacting surface about the instantaneous center as the fixed and movable contacts are in the process of making or breaking. The effect of this motion of the contacting surface is to produce a wiping action of maximum effectiveness between the stationary and movable contacts whereby the contacting surfaces are maintained in a clean condition and their electrical characteristics remain good over a long period of time.

Further, in accordance with the invention a synchronous converter can utilize a contact device as described above. The resilient portion of the movable contact is preferably a substantially planar flat-spring portion. The remaining portion is rigid and extends from the resilient portion at an obtuse angle. A vibrating reed on each excursion applies the deflecting force to the movable contact at a point 'on its rigid portion between the resilient portion and the movable contact surface. This force causes the rigid portion to tend to rotate about an inst-antanueous center of rotation in the plane of the resilient portion and on a normal to the stationary contacting surface where the movable contacting surface touches when the reed is undefiected.

For a more detailed understanding of the invention and for an illustration of the preferred form thereof reference is made to the drawings in which:

FIGURE 1 is a front elevation view of a vibratory reed converter;

FIGURE 2 is a perspective view of one part of the converter of FIGURE 1;

FIGURE 3 is an enlarged schematic view showing the essential elements of a portion of the synchronous converter of FIGURE -1;

FIGURE 4 is a line drawing similar to FIGURE 3.

FIGURE 1 shows a vibratory reed converter which utilizes a driving coil 10 wound about a magnetizable core 12 to provide the driving force. The coil 10 is coupled to an external source, such as a 19 volt 60 cycle source of power, by the connecting wires 14 and 15 so that the core 12, which is desirably of a magnetically soft material, is alternately magnetized in one direction and then another so that its one pole 16 is a north pole for one half of each cycle and a south pole for the other half.

The coil is housed in an electromagnetic shield 20 which is desirably constructed of a magnetically soft material so that it is effective not only to shield the rest -of the converter structure from the magnetic field of coil 10 but also to provide a return path for the flux in core 12. The core 12 is attached to the housing 20 as by the stud 22, which is shown as having its end staked as a means of fastening it to the housing.

A fibre insulator 26 maintains good insulation between one end of the coil 10 and the top of the housing 20. A similar fibre insulator 28 insulates the coil 10 from an electrostatic shield 29. The electrostatic shield 29 is shown as being a thin sheet of electrically conductive material whose periphery is bent to form a cup shape which fits snugly within the interior of housing 20 so that it will shield the remainder of the converter from stray electrical fields of the coil 10. The core 12 is staked at its lower end to hold the shield 29, insulators 26 and 28 and coil 10 in place.

The housing 20 is in turn supported by nonmagnetic supporting members 30 which may, for example, be nonmagnetic stainless steel. They serve to support the driving coil arrangement at the desired spacing from the base 31 of the converter. The converter base 31 also supports the contact assembly and the vibrating reed of the converter.

The vibrating reed 32 which may be made from beryllium copper, for example, carries at one end a magnetic armature 36 which cooperates with the pole 16 of core 12. This armature is shown as being constructed with two permanent magnet portions 38 and 39 which are pinned by iron pins 40 to the vibratory reed 32 so that elements 38 and 39 in conjunction with the iron pins 40 make up a horseshoe type of magnet assembly such that the ends of the elements 38 and 39 which are closely spaced to the pole 16 are of different magnetic polarities. Those ends of the elements 38 and 39 adjacent to poles 16 are spaced apart by a brass spacer 42 which may be pinned to elements 38 and 39 by brass pins 44. The brass spacer may be omitted, however, under some condition-s it is useful as a means for adding mass to the end of the reed 32 so as to change its resonant frequency.

The end of reed 32 opposite that end which carries the armature 36 is fixed between insulating wafers 50 and 51 so as to insulate reed 32 from the remaining elements of the converter. Reed 32 has its fixed end attached to a leadwire 54 which is shown as a ground connection.

The reed 32 also has a separate pusher contact attached to each side of the reed. These pusher contacts are shown at 56' and 57 and may be made of any suitable material. A gold alloy has been found to be a very satisfactory material for this purpose. The pusher contacts 56 and 57 may be each attached to the reed 32 by an adhesive insulating material 58 so that the pusher contacts 56 and 57 are electrically isolated from one another and from the reed 32. The central position of reed 32 as shown in FIG. 1 may be considered to be located symmetrically on the major axis of the converter structure for the other elements are symmetrically positioned about that axis.

On opposite sides of reed 32 fixed or stationary contacts 6'6 and 67 are positioned. Each of these contacts has an end which is clamped in the base stack. For example, the end portion 68 of contact 66 is fixed in the base stack between insulating wafers 70 and 71. Those portions of the contacts 66 and 67 which extend above the base stack may be constructed in a manner which is to be later described in conjunction with FIGURE 2. For the present description it is suflicient to note that the lower portions of contacts 66 and 67 should have a sufficient resilience to provide the necessary bias to maintain the upper portions against their adjustable stops. Contacts 66 and 67 may be of a fairly rigid structure with flanged portions such as 72 and 73.

Contacts 66 and 67 have wire shaped contact elements 76 and 77, respectively, mounted thereon. These wire shaped elements may, for example, be a gold alloy to provide good electrical characteristics. They are preferably mounted so that there is an angular relationship other than 90 between that surface of the wire which is effective as a contacting surface and the direction in which the associated movable contacting surfaces, later to be described, move as they approach the elements 76 and 77, so that there will be a minimization of bounce between the contacts.

The bias of the less rigid portions of the contacts 66 and 67 keeps those contacts against their adjusting screws 80 and 8 1 respectively. Thus screw 80 can be adjusted to position contact 66 by virtue of the contact of screw 80 with the insulating button 82 which is affixed to contact 66. The adjustable screw 80 may have a slotted head 84 to accept a screw driver for adjustment of the screw 80 in the split nut 86 which is held by collar 88 to the supporting element 30. A similar adjusting arrangement for screw 81 is provided to position the stationary contact 67.

In addition to a stationary contact on each side of reed 32 there is also provided an associated movable contact which cooperates with the fixed contacts previously described. Movable contact 90 is shown as cooperating With stationary contact 66 so that its wire shaped contact element 92 near one end of contact 90 provides a contacting surface which will provide good electrical contact with the contacting surface of element 76 of fixed contact 66 upon physical contact therewith. That end of contact 90 which carries contact element 92 is a rigid portion, shown in FIGURE 1 as having flanged sides such as 94. This rigid portion in addition to carrying contact element 92 near its end also carries a pushed contact 96 which is positioned to be pushed by the pusher contact 56.

The other end 98 of the movable contact 90 is fixed between the insulating wafers 51 and in the base stack 31. This arrangement places the fixed end of the movable contact in close spaced relationship with the fixed end of reed 32. The portion 91 of movable contact 90 between its fixed portion and its rigid portion comprises a substantially planar flat-spring which is resilient and which tends to bias the contact element 92 into contact with contact element 76. The rigid portion and the flexible portion of the movable contact constitute a means for resiliently supporting the contact element 92.

The flat-spring portion tends to maintain the pushed contact 96 in contact with the pusher contact 56 when the reed 32 is moved sufficiently toward the right in its oscillating motion. The flat-spring portion of contact 90 is at an obtuse angle with the rigid portion as shown in FIGURE 1. The fiat-spring portion 91 of contact 90 is also at an angle with the converters major axis. This latter angular relationship may desirably be in the range from 30 to 60 degrees and preferably close to 45 degrees for reasons which will become more clear from further explanation of the detailed operation of this converter.

As will be evident from FIGURE 1 movable contact 89 is positioned on the other side of reed 32 from the movable contact 90 and is similarly constructed. Contact 89 cooperates with fixed contact 67 and the pusher contact 57 in the same manner that contact 90 cooperates with fixed contact 66 and pusher contact 56.

The base stack 31 utilizes relatively thick spacers 100 and 101 on opposite sides of the contacts so as to space the contacts for central orientation and firm uniform clamping between the supporting elements 30. The fixed or stationary contacts 66 and 67 and the movable contacts 90 and 89 as well as reed 32 are each spaced and insulated one from the other by insulating wafers as previously mentioned. These insulating wafers along with the spacers 100 and 101 comprise the base stack 31 which is held firmly by the machine screws 104 and 105 in conjunction with the threaded nut plate 108. It Will also be evident from FIGURE 1 that there is provided a copper wafer 109 between the nut plate 108 and the base portion of the right hand supporting member 30. The wafer 109 has attached to it a lead 110 which may be utilized for the purpose of establishing an external ground connection.

Each of the stationary contacts 66 and 67 is provided with an external connecting wire 112 and 113, respectively. Wires 114 and 115 provide for external connection to movable contacts 90 and 89.

The converter of FIGURE 1 may be utilized in either of the usual single-pole double-throw modes such as the break-before-make mode or the make-before-break mode.

Also, the converter may be utilized as two single-pole single-throw contact pairs. For the single-pole doublethrow mode the wires 112 and 113 may be connected. With such a connection the fixed contact elements 76 and 77 act as a common electrical switch element.

As shown in FIGURE 1, the contact elements 92 and 93 are in physical contact with the contact elements 76 and 77 respectively when the reed 32 is centrally positioned between its extreme deflected positions, namely, the position shown in FIGURE 1.

As the reed 32 is deflected to the right such as would be the case when the pole 16 is of such polarity as to differ from the fixed polarity of the magnetic elements 39 the pusher contact 56 pushes on the pushed contact 96 tending to deflect movable contact 90 so as to separate the contact elements 92 and 76. When the energization of the pole 16 is altered the reed 32 is deflected in the opposite direction so that the pusher contact 57 exerts a force on its associated pushed contact 97 to separate element 93 from the stationary contact element 77. With the adjustment as shown in FIGURE 1 the separation of contact element 93 from the contact element 77 will occur after the contact elements 92 and 76 have been remade as when the reed 32 has moved to the left of its central position. This then would be the make-before-break mode of operation. By suitable adjustment of the adjusting screws 80 and 81 the contact elements 76 and 77 can be so positioned that the associated elements 92 and 93 will be separated from them when the reed 32 is centrally positioned. Such an adjustment would provide a break-before-make mode of operation.

With reference to FIGURE 2 the fixed contact 66 is shown in an enlarged perspective view so that the details of construction of that element are more evident. In FIGURE 2 the fixed portion 68 which is held in the base stack 31 has two holes for receiving the machine screws 104 and 105 of FIGURE 1, one hole only being shown. Above the base portion 68 the fixed contact 66 has a rectangular aperture punched through it so that the pusher contact 56 can operate between the remaining side portions 120 and 121 as reed 32 is deflected. This aperture also permits the flat-spring portion 91 to extend therethrough. Above the area from which the aperture is punched the fixed contact 66 may be provided as shown with flanged sides 72 and 125 to lend rigidity to that portion. Also above the portion from which the aperture has been punched the contact elements 76 is positioned in a more or less vertical orientation. As has been previously mentioned the contact element 76 may, for example, be a piece of gold alloy wire. This contact is afiixed to an area of the upper portion which is a coined section, namely section 128 so that the contact element 76 is given the desired angular position with respect to the other elements in the converter assembly of FIGURE 1.

The fixed contact 67 is of similar construction but in FIGURE 1 is positioned with an opposite orientation on the opposite side of reed 32 from fixed contact 66.

The schematic showing in FIGURE 3 illustrates the general structure and the relationships between the several parts such as reed 32, movable contact 90, movable contact element 92, fixed contact element 76, pusher contact 56 and pushed contact 96 as shown in FIGURE 1. The schematic showing of FIGURE 3 is also shown in a more simple line drawing in FIGURE 4 for the purposes of clarifying the explanation as to the operation of the various parts. FIGURE 3 shows the various parts of the contact assembly in solid line to illustrate their relative positions when the reed 32 is in its central position. Those same parts are shown in phantom to illustrate their relative positions when the movable contact element 92 is about to separate from fixed contact element 76.

When the reed 32 is in its central position, as for example, the vertically oriented position shown in FIGURE 3, the resilient or flexible portion 91 of the movable contact 90 is oriented to form an acute angle A with reed 32 which is desirably in the range of 30 to 60 degrees and is preferably close to 45 degrees. The rigid portion 132 extends from the end of the resilient portion 91 so that the included angle between portion 132 and portion 91 is less than 180. In FIGURE 3 this angle is shown as an obtuse angle 13 which faces toward reed 32. This angular relationship places the point of contact between pusher contact 56 and the pushed contact tion 91.

96 outside the plane of the resilient portion 91, which is shown as lying along line 130, by an amount which preferably approximates the length of the resilient por- Also, the abovementioned obtuse angle B places the point of contact between the movable contact element 92 and fixed contact element 76 at a point outside the plane of the resilient portion 91, preferably at a distance of the order of twice the length of the resilient portion 91. In addition to the above relationships it is desirable that the point of contact between the pusher contact '56 and the pushed contact 96 should be spaced from the point of contact between the movable contact element 92 and the fixed contact element 76 by a distance greater than the length of the resilient portion '91. The rigid portion may, as shown in FIGURE 3, have a slight angular relation to reed 32.

While the resilient portion 91 is shown in FIGURE 3 as forming an essentially'flat plane lying along the center line 130, it will be evident that the resilient portion 91 may lie along a curved plane such that its average plane, that is the plane midway between the extreme planes in which areas of the resilient portion 91 may lie, will also fall along the center line 130.

The resilient portion 91 provides a spring bias to the rigid portion 132 so that the pushed contact 96 is maintained in physical contact with the pusher contact 56 at least during the period when reed 32 is deflected to the right of some critical position as established by adjustment of the position of fixed contact element 76. As shown, the rigid portion 132 may be part of the same piece of material which forms the resilient portion 91 as Well as the base portion 98, the rigid portion 132 being rigid by virtue of the outer flanged areas 94 of that portion.

As shown in FIGURE 3, the rigid portion 132 carries at a point near its one end a contact element 92 which is shown as a horizontally oriented piece of wire similar to the fixed or stationary contact 76 which itself is vertically oriented on fixed contact 66.

Considering together both FIGURES 3 and 4 it will be evident that during the initial portion of the period in which reed 32 moves from its solid line position toward the night, the pusher contact 56 tends to move about a center 160 (FIGURE 4) on the lower portion of the axis of reed 32. During this movement pusher contact 56 exerts a force on the pushed contact 96. This force is shown as being applied at the point of contact between contact 56 and contact 96 and is in a direction close to, but not necessarily coincident with, the normal to the plane of contact which normal is shown by the arrow F (FIGURE 3). The pusher contact 56 itself is constrained to move in a manner which may be considered to be around a center such as 160 in the general direction shown by the arrow Pd2 which is established at right angles to the radial line 162 from center 160. At the same time the movable contact 92 is constrained to move about the center 144 which is established at the intersection between the center line which represents the plane of flexible portion 91 and therefore is normal to a line of action of the upper end of 91 shown as arrow and the center line 142, which represents a normal to the plane of contact between the fixed contact element 76 and the movable contact element 92 when the reed 32 is in its undefiected position. It will thus be evident that the effect of the force F of the pusher contact 56 on the pushed contact 96 is to tend to move contact 96 at right angles to the radial line 164 from center 144 in the direction shown by the arrow Pdl. As a result of the spring bias introduced by the resilient flat-spring portion 91, contact 92, during the initial portion of the deflection of reed 32 to the right, would be constrained to follow a path which maintains the contact element 92 in contact with the element 76 until the bias of the flat-spring portion 91 is overcome by the force exerted by the pusher contact 56. Then contact 92 is ready to be separated from contact with element 76. During this transition period,

the breaking period, the pushed contact element 96 would tend to move in a direction indicated by the arrow Pdll while the pusher contact 56 will tend to move in a direction indicated by the arrow PdZ. These directions being different there would be a wiping movement of the pusher contact 56 over the surface of the pushed contact 96.

As reed 32 moves toward the right the force between contact elements 56 and 96 increases and the force between contact elements 76 and 92 decreases and when the latter reaches zero the elements are in the position shown by the phantom lines of FIGURE 3. Immediately thereafter contact element 92 leaves and becomes separated from the contact element 76. The amount of wipe between contact elements 76 and 92 is shown by the distance between the full and phantom position of contact element 92. The amount of wipe (up to this moment) between contact elements 56 and 96 is less apparent but could be obtained as the difference between measurements on the full FIGURE 3 and those on the phantom FIG- URE 3. Line 150 points to the point of contact of contact element 56 in its initial or full line position and line 152 points to the point of contactof contact element 56 in its later or phantom line position. This point :has moved down, however, contact element 96 has moved down more as shown by the relation of its phantom position to its full position. The net result is a wiping motion of contact element 56 in an upward direction on contact element 96 which in magnitude is the difference in the motion of the two contact elements. For clarity of illustration the amount of wipe is shown greater than the amount generally observed. In attaining one object of this invention it is desirable to minimize further wipe between contact elements 56 and 96. After this separation occurs the movable contact 90 is no longer constrained by contact element 76 and contact element 96 can move in the same direction as the pusher contact 56, namely, the direction shown by the arrow P112 (FIGURE 4). This results from the fact that the frictional forces between the pusher contact 56 and pushed contact 96 are sufficient to maintain them in relatively fixed positional relationship one with the other and to prevent any tendency of one to slide over the other. This action is possible because of the freedom of the movable contact 90 to move about the center 166 which is at the intersection of line 130 and line 160. Then pusher contact 56 and pushed contact 96 are both able to move in the direction PM and therefore for a considerable portion of the further deflection of reed 32 there will be no further sliding or wiping contactbetween them.

The restraints on the motion of the rigid portion 132 of the movable contact 90 introduced by the fixed contact element 76 and pusher contact 56 during the transition period cause the flat-spring portion 91 to tend to take an S shape during its deflection. This S shape can also be caused by the friction of the pusher contact 56 alone after the contact element 92 has separated from contact element 76.

Should the deflection of reed 32 be extreme in amplitude it is possible that the S type deflection to which the flexible portion 91 will be subjected when contacts 56 and 96 are moving together will attempt to revert to a more normal C type deflection and the pushed contact 96 may attempt to pivot about a center 168 in portion 91. The pushed contact 96 would then tend to move in a direction indicated by the arrow Pd3 which is perpendicular to the construction line 169 to the center 168. While the pushed contact 96 is following a path in the direction of the arrow Pd3, the pusher contact 56 will continue to follow a path similar to that shown by the arrow Pd2. These paths being in different directions there will be relative motion between the pusher contact 56 and the pushed contact 96.

From the above description it will be evident that while there is a wiping action in the initial portion of the reed deflection and possibly in the final portion of the reed deflection, such relative motion is minimized by the structure shown in which the point of contact between the pusher contact and the pushed contact lies substantially outside of the plane of the flexible portion 91 of the movable contact.

It will also be evident by reference to FIGURE 3 that the movable contact element 92 as it moves about the center 144 during the initial deflection of reed 32 has its own surface skidding over the surface of the fixed contact element 76 in the direction indicated by the arrow T as evidenced by the distance between the solid line and the phantom line positions. This skidding action, which results from the structure shown in FIGURE 3 which has contact 92 outside of the plane 130 of flexible portion 91, serves to keep both the fixed contact element 76 and the movable contact element 92 substantially free from the type of deposits which would increase the resistance of their electrical contact. Thus, with the elements of the contact assembly having the geometrical relationships best illustrated in FIGURES 3 and 4, the desirable long term stability of the electrical contact, namely, contact elements 92 and 76 is maintained at the same time that the wear between the pusher contact 56 and the pushed contact 96 is minimized so as to maintain the high degree of stability in contact timing. The above described contact action is reversed in direction and sequence as the reed 32 returns to its central or starting position and contact element 92 makes with contact element 76. Thus the contact element 92 wipes or skids over contact element 76 during the making period in similar fashion as previously described for the breaking period.

While the above description concerns the action of the elements of the contact assembly when the reed 32 is deflected to the right of its central position, a similar action will take place when the reed 32 is deflected to the left of its central position since the contact assembly is symmetrically oriented about the reed as shown in FIGURE 1.

What is claimed is:

1. A device for opening and closing electrical circuits comprising,

a stationary contact having a contacting surface,

a movable contact having a contacting surface adapted for movement into and out of contact with the contacting surface of said stationary contact, said movable contact including a resilient portion and a rigid portion, one end of said resilient portion being fixed and said rigid portion extending from the other end, said rigid portion carrying the contacting surface of said movable contact at a point spaced from said other end of said resilient portion and outside of that plane to which the line of action of said other end of said resilient portion is normal,

means operable to exert a deflecting force on said rigid portion at a point outside of said plane by a distance approximately the length of said resilient portion and intermediate between the contacting surface of said movable contact and said other end of said resilient portion and in a direction tending to separate said contacting surfaces by movement of said rigid portion about an instantaneous center of action spaced from the contacting surface of said movable contact.

2. A device as set forth in claim 1 in which said resilient portion forms an obtuse included angle with said rigid portion of said support means and in which the plane of contact between said stationary contact and said movable Contact forms an angle other than with the direction of movement of said movable contact surface.

3. A device as set forth in claim 1 in which said resilient portion forms an obtuse included angle with said rigid portion of said support means.

4. device for opening and closing electrical circuit comprising,

a stationary contact having a contacting surface,

a movable contact having a contacting surface adapted for movement into and out of contact with the con- 3,275,781 9 1t) tacting surface of said stationary contact, said mov- 7. A device for opening and closing electrical circuits able contact including a resilient portion and a rigid comprising, portion, one end of said resilient portion being fixed a stationary contact having a contacting surface, and said rigid portion extending from the other end, a movable contact having a contacting surface adapted surface of said movable contact.

said rigid portion carrying the contacting surface of 5 for movement into and out of contact with the consaid movable contact at a point spaced from said tacting surface of said stationary contact, said movother end of said resilient portion and outside of that able contact including a resilient flat-spring portion plane to which the line of action of said other end of and a rigid portion, one end of said flat-spring porsaid resilient portion is normal, tio-n being fixed and said rigid portion extending from means operable to exert a deflecting force on said rigid the other end, said rigid portion carrying the contactportion at a point outside of said plane by a distance ing surface of said movable contact at a point spaced approximating the length of said resilient portion and from said other end of said resilient portion and outintermediate between the contacting surface of said side of that plane to which the line of action of said movable contact and said other end of said resilient other end of said resilient portion is normal, portion and spaced from said movable contacting surmeans operable to exert a deflecting force on said rigid face by a distance greater than the length of said reportion at a point outside of said plane and intermesilient portion, said force being exerted in a direcdiate between the contacting surface of said movable 'tion tending to separate said contacting surfaces by contact and said other end of said resilient portion movement of said rigid portion about an instanand in a direction tending to separate said contacting taneous center of action spaced form the contacting surfaces by movement of said rigid portion about an instantaneous center of action spaced from the con- 5. A device for opening and closing electrical circuits comprising,

a stationary contact having a contacting surface, a movable contact having a contacting surface adapted for movement into and out of contact with the contacting surface of said movable contact on a side opposite from the contacting surface of said stationary contact whereby the contacting surface of said movable contact skids across that of said stationary contact as said contacting surfaces are being separated tacting surface of said stationary contact, said movand remade. able contact including .a resilient fiat-spring portion 8. A device for opening and closing electrical circuits and a rigid portion, one end of said fiat-spring porcomprising,

tion being fixed and said rigid portion extending from the other end, said rigid portion carrying the cona stationary contact having a contacting surface, a movable contact having a contacting surface adapted tacting surface of said movable contact at a point spaced from said other end of said resilient portion and spaced by a distance approximately twice the tacting surface of said stationary contact, said movable contact including a resilient flat-spring portion and a rigid portion, one end of said flat-spring portion for movement into and out of contact with the contacting surface of said stationary contact, said movable contact including a resilient fiat-spring portion length of said resilient portion outside of that plane and a rigid portion, one end of said flat-spring porto which the line of action of said other end of said tio-n being fixed and Said rigid Portion extending from resilient portion is normal, the other end, said rigid portion carrying the contactmeans operable to exert a deflecting force on said rigid g Surface of Said movable Contact at a Point Spaced portion at a point outside of aid plane d i t from said other end of said resilient portion and outdiate between the contacting surface of said movable Side of that Plane to which the lhle of action of Said; contact and said other end of said resilient portion othor end of Said rosihoht Portion is normal, and in a direction tending to separate said contactmeans operable to exert a deflecting force on Said rigid ing surfaces by movement of said rigid portion about portion at a point intermediate between the contactan in tanta ou enter f ti spaced f h ing surface of said movable contact and said other contacting Surface f id bh t t, end of said resilient portion and in a direction tend- 6. A device for opening and closing electrical circuits ing to Separate Said contacting Surfaces y m comprising, ment of said rigid portion about an instantaneous a stationary onta t having a o t ti Surface, center of action spaced from the contacting surface a movable contact having a contacting surface adapted of Said movable Contact oh 3 Side pp from the for movement into and out of contact with the con- Contacting Surface of Said Stationary Contact whereby the contacting surface of said movable contact skids across that of said stationary contact as said contacting surfaces are being separated and remade.

9. A device for opening and closing electrical circuits comprising,

a stationary contact having a contacting surface,

a movable contact having a contacting surface adapted being fixed and said rigid portion extending from the other end, said rigid portion carrying the contacting surface of said movable contact at a point spaced from said other end of said resilient portion and spaced by a distance approximately twice the length of said resilient portion outside of that plane to which for movement into and out of contact with the contacting surface of said stationary contact, said movthe line of action of said other end of said resilient able ho mciuding a resilient flat'springporfion portion is normal and a r gid portion, one end of said fl at-sprmg pormeans operable to exert a deflecting force on said rigid E 12 g a ig S pf-Jrtlon i i f portion at a point outside of said plane and inter- 0m o en Sal For Ion carrymg e mediate between the contacting surface of said movcontacupg Sm ace of Sal-d mo-v-able Contact Spaced from said other end of said resillent portion and outa l other f sad reslheflt side of the plane to which the line of action of said t1on and m a dlrectlon tendlng i P to Sald 0011' other end of said resilient portion is normal during taotlhg shttaoos by movement of sold Ilgld Pottton the making and breaking of said contacting surfaces, about all Instantaneous Center of action pa from means operable to alternately increase and decrease a the contacting surface of said movable contact on a deflecting force on said rigid portion at a point outside opposite from the contacting surface of said staside of said plane and intermediate between the contionary contact, whereby the contacting surface of tacting surface of said movable contact and said said movable contact skids across that of said stationother end of said resilient portion and in a direction ary contact as said contacting sufaces are being sepatending to separate said contacting surfaces by moverated and remade. ment of said rigid portion in one sense about an instantaneous center of action spaced from the contacting surface of said movable contact as said force is increased and to tend to bring together said contacting surfaces as said force is decreased by movement of said rigid portion about said instantaneous center in an opposite sense, whereby the contacting surface of said movable contact is forced to move across that of said stationary contact during the making and breaking of said contacting surfaces.

10. A device for opening and closing electrical circuits comprising,

a stationary contact having a contacting surface,

a movable contact having a contacting surface adapted for movement into and out of contact with the contacting surface of said stationary contact, said movable contact including a resilient flat-spring portion and a rigid portion, one end of said flat-spring portion being fixed and said rigid portion extending from the other end, said rigid portion carrying the contacting surface of said movable contact at a point spaced from said other end of said resilient portion and outside of the plane to which the line of action of said other end of said resilient portion is normal,

means operable to exert a decreasing force on said rigid portion at a point outside of said plane and intermediate between the contacting surface of said movable contact and said other end of said resilient portion and in a direction to allow said contacting surfaces to remake by movement of said rigid portion about an instantaneous center of action spaced from the contacting surface of said movable contact on a side opposite from the contacting surface of said stationary contact whereby the contacting surface of said movable contact is forced to skid across that of said stationary contact as said contacting surfaces are remade.

11. A device for opening and closing electrical circuits comprising,

a stationary contact having a contacting surface,

a movable contact having a contacting surface adapted for movement into and out of contact with the contacting surface of said stationary contact, said movable contact including a resilient fiat-spring portion and a rigid portion, one end of said flat-spring portion being fixed and said rigid portion extending from the other end, said rigid portion carrying the contacting surface of said movable contact at a point spaced from said other end of said resilient portion and outside of the plane to which the line of action of said other end of said resilient portion is normal,

means operable to exert a decreasing force on said rigid portion at a point outside of said plane and intermediate between the contacting surface of said movable contact and said other end of said resilient portion and in a direction to allow said contacting surfaces to remake by movement of said rigid portion about an instantaneous center of action spaced from the contacting surface of said movable contact whereby the contacting surface of said movable contact is forced to skid across that of said stationary contact as said contacting surfaces are remade.

12. A device for opening and closing electrical circuits comprising,

a stationary contact having a contacting surface,

a movable contact having a contacting surface adjacent to one end thereof, said other end being fixed to allow movement of the contacting surface of said movable contact into and out of contact with the contacting surface of said stationary contact, a portion of said movable contact adjacent to said fixed end being flexible in character,

means operable to exert a varying force on said movable contact at a point between said fixed end and said contacting surface and in a direction tending to cause the contacting surface of said movable contact to move about an instantaneous center which is in an average plane of that resilient portion lying between said fixed end and said point of force application and spaced from the contacting surface of said movable contact so that said center is on that side of the contacting surface of said movable contact opposite from the contacting surface of said stationary contact whereby said movement has a tangential component of the motion of the contacting surface of said movable contact about said center which is in the same direction as motion of said contacting surface of said movable contact along said contacting surface of said fixed contact .as said force is changed to alter the relationship of said surfaces.

13. A synchronous converter comprising,

a driving coil energizable by alternating current,

a vibratory reed having a fixed end and carrying an armature structure at its other end, said armature structure being responsive to the alternating flux of said coil to effect a vibration of the reed,

a stationary contact element positioned on each side of said reed,

a separate resiliently mounted contact element on each side of said reed, said resiliently mounted contact elements each being positioned to engage the associated stationary contact element at certain positions of said reed, each of said resilient mountings for said contact elements having a substantially planar flat-spring portion lying in a plane forming with said reed an angle which is in the range between 30 and 60 with one end of said fiat-spring portion being fixed in close spaced relationship with said fixed end of said reed and said resilient mountings also having a rigid portion extending from the other end of said fiat-spring portions and at an obtuse included angle so that said resiliently mounted contact elements are spaced a distance outside the planes of the respective resilient portions which is approximately twice the length of said flat-spring portion when said reed is centrally positioned,

a pusher contact mounted on each side of said reed,

a pushed contact mounted on said rigid portion of each of said resilient mountings so that the vibratory motion of said reed causes said pusher contacts to alternately apply a force to each of said Pushed contacts so as to deflect said rigid portions to break the contact elements on one side and make the contact elements on the other side of said reed during each half cycle of said vibratory motion.

14. A synchronous converter as set forth in claim 13 in which said stationary contact element is oriented to present a surface to said resiliently mounted contact element which is at an angle other than to the direction of movement of said resiliently mounted contact element as it engages said stationary contact element.

15. A synchronous converter as set forth in claim 13 in which the deflections of said rigid portions by said pusher contacts is in a direction to cause the said flatspring portion to distort to an S shaped contour whereby said pusher contacts and said pushed contacts are maintained in a fixed contacting relationship after said resilient- 1y mounted contact elements are separated from said stationary contact elements.

16. A synchronous converter comprising,

a driving coil energizable by alternating current,

a vibratory reed having a fixed end and carrying an armature structure at its other end, said armature structure being responsive to the alternating flux of said coil to effect a vibration of the reed,

a stationary contact element positioned on each side of said reed,

a separate resiliently mounted contact element on each side of said reed, said resiliently mounted contact elements each being positioned to engage the associated stationary contact element at certain positions of said reed, each of said resilient mountings for said contact elements having a substantially planar flat-spring portion lying in a plane forming with said reed an angle which is in the range between 30 and 60 with one end of said flat-spring portion being fixed and said resilient mountings also having a rigid portion extending from the other end of said fiat-spring portions and at an obtuse included angle so that said resiliently mounted contact elements are spaced a distance outside the planes of the respective resilient portions which is approximately twice the length of said flat-spring portion when said reed is centrally positioned,

a pusher contact mounted on each side of said reed,

a pushed contact mounted on said rigid portion of each of said resilient mountings so that the vibratory motion of said reed causes said pusher contacts to alternately apply a force to each of said pushed contacts so as to deflect said rigid portions to break the contact elements on one side and make the contact elements on the other side of said reed during each half cycle of said vibratory motion.

17. A synchronous converter comprising,

a driving coil energizable by alternating current,

a vibratory reed having a fixed end and carrying an armature structure at its other end, said armature structure being responsive to the alternating flux of said coil to effect a vibration of the reed,

a stationary contact element positioned on each side of said reed,

a separate resiliently mounted contact element on each side of said reed, said resiliently mounted contact elements each being positioned to engage the associ-' ated stationary contact element at certain positions of said reed, each of said resilient mountings for said contact elements having a substantially planar fiat-spring portion lying in a plane forming with said reed an angle which is in the range between 30 and 60 with one end of said fiat-spring portion being in closed spaced relationship with said fixed end of said reed and said resilient mountings also having a rigid portion extending from the other end of said flat-spring portions and at an obtuse included angle facing said reed so that said resiliently mounted contact elements are spaced at distance outside the planes of the respective resilient portions at least equal to twice the length of said flat-spring portion when said reed is centrally positioned,

a pusher contact mounted on each side of said reed,

a pushed contact mounted on said rigid portion of each of said resilient mountings so that the vibratory motion of said reed causes said pusher contacts to alternately apply a force to each of said pushed contacts so as to deflect said rigid portions to break the contact elements on one side and make the contact elements on the other side of said reed during each half cycle of said vibratory motion.

18. A synchronous converter as set forth in claim 17 in which said pushed contacts are positioned on said rigid portions so that the distance between the point of contact of each of said pushed contacts with its associated pusher contact and the point of contact of the corresponding stationary contact element with its associated resiliently mounted contact element is at least equal to the length of said flat spring portion.

19. A synchronous converter as set forth in claim 18 in which said point of contact between each of said pusher contacts and its associated pushed contact is spaced from the plane of the corresponding resilient portion a distance at least equal to the length of said flat-spring portion.

20. A device for opening and closing electrical circuits comprising,

a stationary contact element,

a movable contact element,

means for resiliently supporting said movable contact element so that it is free to move into and out of electrical contact with said stationary contact element, said means for supporting said movable contact element having a resilient fiat-spring portion with a fixed end, and a rigid portion extending from the other end of said resilient portion and supporting said movable contact at a point spaced from said other end of said resilient portion and outside that plane normal to the line of action of said other end of said resilient portion,

means operable at a point on said rigid portion outside of said plane and intermediate between said movable contact element and said other end of said resilient portion to apply to said rigid portion for a period of time a force having a component which does not fall along a radius of the instantaneous center of action of said rigid portion in the initial phases of its motion as said force tends to move said movable contact from its undeflected position whereby said movable contact is moved across said stationary contact with a maximum effectiveness of wiping action during the contact making and breaking period.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner. 

12. A DEVICE FOR OPENING AND CLOSING ELECTRIC CIRCUITS COMPRISING, A STATIONARY CONTACT HAVING A CONTACTING SURFACE, A MOVABLE CONTACT HAVING A CONTACTING SURFACE ADJACENT TO ONE END THEREOF, SAID OTHER END BEING FIXED TO ALLOW MOVEMENT OF THE CONTACTING SURFACE OF SAID MOVABLE CONTACT INTO AND OUT OF CONTACT WITH THE CONTACTING SURFACE OF SAID STATIONARY CONTACT, A PORTION OF SAID MOVABLE CONTACT ADJACENT TO SAID FIXED END BEING FLEXIBLE IN CHARACTER, MEANS OPERABLE TO EXERT A VARYING FORCE ON SAID MOVABLE CONTACT AT A POINT BETWEEN SAID FIXED END AND SAID CONTACTING SURFACE AND IN A DIRECTION TENDING TO CAUSE THE CONTACTING SURFACE OF SAID MOVABLE CONTACT TO MOVE ABOUT AN INSTANTANEOUS CENTER WHICH IS IN 